Schools tapping A/C condensate to conserve water

By TAYLOR McGILVRAY and LOUIS CASIANO, HOUSTON CHRONICLE

Published 7:20 pm, Monday, September 19, 2011

Photo: Nathan Lindstrom

Image 1of/1

Caption

Close

Image 1 of 1

NATHAN LINDSTRON : FOR THE CHRONICLE
MILLIONS OF GALLONS: Rice University's BioScience Research Collaborative building can be seen between giant cooling towers on top of the university's south power plant. Rice uses water condensed in the building's air conditioners to replace water lost to evaporation. less

NATHAN LINDSTRON : FOR THE CHRONICLE
MILLIONS OF GALLONS: Rice University's BioScience Research Collaborative building can be seen between giant cooling towers on top of the university's south power plant. ... more

Photo: Nathan Lindstrom

Schools tapping A/C condensate to conserve water

1 / 1

Back to Gallery

Two Houston universities are tapping into one of the city's defining features - air conditioning - to conserve water in the midst of a historic drought.

Rice University is recycling 12 million gallons of water per year, 5 percent to 6 percent of its annual water consumption, by harvesting condensate water, or gray water, from air-conditioning units on campus. The initiative will save the university about $80,000 to $100,000 per year.

Across town at the University of Houston, officials started recycling water for three science buildings five years ago and plan to expand the initiative to new buildings being constructed.

"In a typical year, adding water to the cooling tower is our biggest portion of our water consumption," said Richard Johnson, director of energy and sustainability at Rice. "So, to the extent to which we can find ways to find water to recycle to use in our cooling tower, it means that we need less water from the city of Houston."

Already distilled

Rice began the initiative in fall 2008 in its BioScience Research Collaborative building, a 10-story, science-intensive building that requires a lot of cooling and creates a lot of condensate.

"The great thing about this condensate water (is) it's pure, you don't need to treat it," Johnson said. "It's distilled water, and it's cold."

The condensate is used to replace water lost to evaporation without having to get it all from the city water supply.

Another project that collects condensate from eight buildings on campus was finished this summer.

"It (was) real easy to complete that project because the buildings were already designed to accommodate that collection of water," said Erik Knezevich, project manager and engineer at Rice.

Such projects work best in buildings designed for recapturing water. Capturing condensate in older buildings can require costly steps such as pumping water through pipes with a lot of turns and slopes, Johnson said.

"The pumps we use don't require a lot of energy," Johnson said. "The amount of water saved would more than offset the electricity we use."

Reducing costs

At UH, water recycling began when officials noticed a large amount of water being wasted from the cooling towers.

"We noticed so much water was just going down the drain," said Sameer Kapileshwari, director for facilities operations and maintenance. "We were losing about 8,000 gallons of water a day."

Kapileshwari said the recycling project has reduced the university's water and energy costs.

The concept is catching on slowly around the country, said Rice's Knezevich.

"It's usually referred to as gray water recovery, which is a big environmental movement across the country. There are different variations of how you collect your water and ways in which you reuse it," Knezevich said. "It's certainly a great opportunity for buildings that use a lot of air conditioning."

Keith Morrison, a 23-year-old chemistry major at Rice, likes the idea of his campus taking green initiatives.

"I think it's great," Morrison said. "It saves (Rice) money while conserving water. We should do more things like this."

Latest from the Chron.com Homepage

Click below for the top news from around the Houston area and beyond. Sign up for our newsletters to be the first to learn about breaking news and more. Go to 'Sign In' and 'Manage Profile' at the top of the page.